别再用 BeanUtils 了，这款 PO VO DTO 转换神器不香么？

发布时间：2021-09-20 13:37:29来源：ImportNew

先贴下官网地址吧：https://mapstruct.org/

废话不多说，上代码：

pom配置：

UTF-81.81.81.4.1.Final1.18.12org.mapstructmapstruct${org.mapstruct.version}org.projectlomboklombok${org.projectlombok.version}providedorg.mapstructmapstruct-processor${org.mapstruct.version}providedorg.apache.maven.pluginsmaven-compiler-plugin3.8.11.81.8org.projectlomboklombok${org.projectlombok.version}org.mapstructmapstruct-processor${org.mapstruct.version}关于lombok和mapstruct的版本兼容问题多说几句，maven插件要使用3.6.0版本以上、lombok使用1.16.16版本以上，另外编译的lombokmapstruct的插件不要忘了加上。否则会出现下面的错误：Nopropertynamed"aaa"existsinsourceparameter(s).Didyoumean"null"?

这种异常就是lombok编译异常导致缺少getsetter方法造成的。还有就是缺少构造函数也会抛异常。

@Data@Builder@AllArgsConstructor@NoArgsConstructorpublicclassStudent{privateStringname;privateintage;privateGenderEnumgender;privateDoubleheight;privateDatebirthday;}publicenumGenderEnum{Male("1","男"),Female("0","女");privateStringcode;privateStringname;publicStringgetCode(){returnthis.code;}publicStringgetName(){returnthis.name;}GenderEnum(Stringcode,Stringname){this.code=code;this.name=name;}}@Data@Builder@AllArgsConstructor@NoArgsConstructorpublicclassStudentVO{privateStringname;privateintage;privateStringgender;privateDoubleheight;privateStringbirthday;}@MapperpublicinterfaceStudentMapper{StudentMapperINSTANCE=Mappers.getMapper(StudentMapper.class);@Mapping(source="gender.name",target="gender")@Mapping(source="birthday",target="birthday",dateFormat="yyyy-MM-ddHH:mm:ss")StudentVOstudent2StudentVO(Studentstudent);}实体类是开发过程少不了的，就算是用工具生成肯定也是要有的，需要手写的部分就是这个Mapper的接口，编译完成后会自动生成相应的实现类

然后就可以直接用mapper进行实体的转换了

publicclassTest{publicstaticvoidmain(String[]args){Studentstudent=Student.builder().name("小明").age(6).gender(GenderEnum.Male).height(121.1).birthday(newDate()).build();System.out.println(student);//这行代码便是实际要用的代码StudentVOstudentVO=StudentMapper.INSTANCE.student2StudentVO(student);System.out.println(studentVO);}}mapper可以进行字段映射，改变字段类型，指定格式化的方式，包括一些日期的默认处理。

可以手动指定格式化的方法：

@MapperpublicinterfaceStudentMapper{StudentMapperINSTANCE=Mappers.getMapper(StudentMapper.class);@Mapping(source="gender",target="gender")@Mapping(source="birthday",target="birthday",dateFormat="yyyy-MM-ddHH:mm:ss")StudentVOstudent2StudentVO(Studentstudent);defaultStringgetGenderName(GenderEnumgender){returngender.getName();}}上面只是最简单的实体映射处理，下面介绍一些高级用法

属性映射基于上面的mapping配置

@MapperpublicinterfaceStudentMapper{StudentMapperINSTANCE=Mappers.getMapper(StudentMapper.class);@Mapping(source="gender.name",target="gender")@Mapping(source="birthday",target="birthday",dateFormat="yyyy-MM-ddHH:mm:ss")StudentVOstudent2StudentVO(Studentstudent);Liststudents2StudentVOs(ListstudentList);}publicstaticvoidmain(String[]args){Studentstudent=Student.builder().name("小明").age(6).gender(GenderEnum.Male).height(121.1).birthday(newDate()).build();Listlist=newArrayList<>();list.add(student);Listresult=StudentMapper.INSTANCE.students2StudentVOs(list);System.out.println(result);}2.多对象转换到一个对象@Data@Builder@AllArgsConstructor@NoArgsConstructorpublicclassStudent{privateStringname;privateintage;privateGenderEnumgender;privateDoubleheight;privateDatebirthday;}@Data@AllArgsConstructor@Builder@NoArgsConstructorpublicclassCourse{privateStringcourseName;privateintsortNo;privatelongid;}@Data@Builder@AllArgsConstructor@NoArgsConstructorpublicclassStudentVO{privateStringname;privateintage;privateStringgender;privateDoubleheight;privateStringbirthday;privateStringcourse;}@MapperpublicinterfaceStudentMapper{StudentMapperINSTANCE=Mappers.getMapper(StudentMapper.class);@Mapping(source="student.gender.name",target="gender")@Mapping(source="student.birthday",target="birthday",dateFormat="yyyy-MM-ddHH:mm:ss")@Mapping(source="course.courseName",target="course")StudentVOstudentAndCourse2StudentVO(Studentstudent,Coursecourse);}publicclassTest{publicstaticvoidmain(String[]args){Studentstudent=Student.builder().name("小明").age(6).gender(GenderEnum.Male).height(121.1).birthday(newDate()).build();Coursecourse=Course.builder().id(1L).courseName("语文").build();StudentVOstudentVO=StudentMapper.INSTANCE.studentAndCourse2StudentVO(student,course);System.out.println(studentVO);}}3.默认值@MapperpublicinterfaceStudentMapper{StudentMapperINSTANCE=Mappers.getMapper(StudentMapper.class);@Mapping(source="student.gender.name",target="gender")@Mapping(source="student.birthday",target="birthday",dateFormat="yyyy-MM-ddHH:mm:ss")@Mapping(source="course.courseName",target="course")@Mapping(target="name",source="student.name",defaultValue="张三")StudentVOstudentAndCourse2StudentVO(Studentstudent,Coursecourse);}

转自：toutiao.com/i6891531055631696395

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